std::basic_string<CharT,Traits,Allocator>::data

 

C++

Compiler support

Freestanding and hosted

Language

Standard library headers

Named requirements

Feature test macros (C++20)

Language support library

Concepts library (C++20)

Metaprogramming library (C++11)

Diagnostics library

General utilities library

Strings library

Containers library

Iterators library

Ranges library (C++20)

Algorithms library

Numerics library

Localizations library

Input/output library

Filesystem library (C++17)

Regular expressions library (C++11)

Concurrency support library (C++11)

Technical specifications

Symbols index

External libraries

 

Strings library

Null-terminated strings

Byte strings

Multibyte strings

Wide strings

Classes

basic_string

basic_string_view (C++17)

char_traits

 

std::basic_string

Member functions basic_string::basic_string basic_string::operator= basic_string::assign basic_string::get_allocator Element access basic_string::at basic_string::operator[] basic_string::front (C++11) basic_string::back (C++11) basic_string::data basic_string::c_str basic_string::operator  basic_string_view (C++17) Iterators basic_string::beginbasic_string::cbegin (C++11) basic_string::endbasic_string::cend (C++11) basic_string::rbeginbasic_string::crbegin (C++11) basic_string::rendbasic_string::crend (C++11) Capacity basic_string::empty basic_string::sizebasic_string::length basic_string::max_size basic_string::reserve basic_string::capacity basic_string::shrink_to_fit (C++11)   Operations basic_string::clear basic_string::insert basic_string::erase basic_string::push_back basic_string::pop_back (C++11) basic_string::append basic_string::operator+= basic_string::compare basic_string::starts_with (C++20)   basic_string::ends_with (C++20) basic_string::contains (C++23) basic_string::replace basic_string::substr basic_string::copy basic_string::resize basic_string::resize_and_overwrite (C++23) basic_string::swap

Search basic_string::find basic_string::rfind basic_string::find_first_of basic_string::find_first_not_of basic_string::find_last_of basic_string::find_last_not_of Constants basic_string::npos Deduction guides (C++17) Non-member functions operator+ swap(std::basic_string) operator""s (C++14) erase(std::basic_string)erase_if(std::basic_string) (C++20)(C++20) I/O operator<<operator>> getline Comparison operator==operator!=operator<operator>operator<=operator>=operator<=> (until C++20)(until C++20)(until C++20)(until C++20)(until C++20)(C++20) Numeric conversion stoistolstoll (C++11)(C++11)(C++11) stoulstoull (C++11)(C++11) stofstodstold (C++11)(C++11)(C++11) to_string (C++11) to_wstring (C++11) Helper classes hash<std::string>hash<std::wstring>hash<std::u32string>hash<std::u16string>hash<std::u8string> (C++11)  (C++11)(C++11)(C++11)(C++20) hash<std::pmr::string>hash<std::pmr::wstring>hash<std::pmr::u32string>hash<std::pmr::u16string>hash<std::pmr::u8string> (C++17)(C++17)(C++17)(C++17)(C++20)

 

	(1)
const CharT* data() const;			(until C++11)
const CharT* data() const noexcept;			(since C++11) (until C++20)
constexpr const CharT* data() const noexcept;			(since C++20)
		(2)
CharT* data() noexcept;				(since C++17) (until C++20)
constexpr CharT* data() noexcept;				(since C++20)

Returns a pointer to the underlying array serving as character storage. The pointer is such that the range

 [data(); data() + size()) (until C++11)

 [data(); data() + size()] (since C++11)

is valid and the values in it correspond to the values stored in the string.

The returned array is not required to be null-terminated. If empty() returns true, the pointer is a non-null pointer that should not be dereferenced.	(until C++11)
The returned array is null-terminated, that is, data() and c_str() perform the same function. If empty() returns true, the pointer points to a single null character.	(since C++11)

The pointer obtained from data() may be invalidated by:

• Passing a non-const reference to the string to any standard library function, or
• Calling non-const member functions on the string, excluding operator[](), at(), front(), back(), begin(), end(), rbegin(), rend().

1) Modifying the character array accessed through the const overload of data has undefined behavior.

2) Modifying the past-the-end null terminator stored at data()+size() to any value other than CharT() has undefined behavior.

Parameters

(none)

Return value

A pointer to the underlying character storage.

data()[i] == operator[](i) for every i in [0, size()).	(until C++11)
data() + i == std::addressof(operator[](i)) for every i in [0, size()].	(since C++11)

Complexity

Constant.

Example

Run this code

#include <algorithm>
#include <cassert>
#include <cstring>
#include <string>
 
int main()
{
  std::string const s("Emplary");
  assert(s.size() == std::strlen(s.data()));
  assert(std::equal(s.begin(), s.end(), s.data()));
  assert(std::equal(s.data(), s.data() + s.size(), s.begin()));
  assert(0 == *(s.data() + s.size()));
}

See also

front (C++11)	accesses the first character (public member function)
back (C++11)	accesses the last character (public member function)
c_str	returns a non-modifiable standard C character array version of the string (public member function)
data (C++17)	returns a pointer to the first character of a view (public member function of std::basic_string_view<CharT,Traits>)